CHAPTER X. 



FARM MECHANICS. 



Work. The word ivork is used in various senses. It 

 will here be used in its scientific sense — that of moving 

 against resistance. The mere push or pull of a force 

 is not work ; the point of application of the force must 

 move before work can be said to be done. A foot-pound 

 of work is done when a force of one pound moves its 

 point of application through a distance of one foot in 

 the direction of the force. 



501. How much work is done by a force of 20 pounds 

 when its point of application moves 30 feet in the direc- 

 tion of the force? 



Process: 20 X -iU = 600 Foot-pounds of work. 



502. How much work is done when a 160-pound man 

 climbs to the top of a 40-foot windmill ? 



503. How much work is done when a 120-pound boy 

 walks up one flight of stairs to a second floor which is 10 

 feet above the first? Ans. 1.200 foot-pounds. 



504. How much work does a 1.200-pound horse do in 

 walking up a hill 1 00 feet high ? 



505. The draft of (the force required to pull) a cer- 

 tain hand cart is 15 ]X)unds. How much work does a boy 

 do in pushing it a mile ? 



Process : 5,280 X 15 = 79,200- Foot-pounds. 



506. How much work is done by a team in plowing 

 a furrow 40 rods long when the draft of the jilow is t>00 

 pounds? 



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